They are fine as long as you break them in properly and run good oil--have never had a problem and have used many. Most recent being in two 327's we did.
Used for many years, what kind of experience and knowledge that you need to know? Easy enough (IMO), lube cam, run at 2500 or so for 20 minutes. I guess the major thing is to make sure you know how to set an engine up to fire it off ASAP.
Last season I experienced a wiped cam on my model A with sbc. The cam had lasted 2 seasons before it let go. My pickup with flathead engine has run for 20 seasons now without a problem. The difference is spring pressure I believe. The more radical cams require high spring pressure which puts a heavy load on the camshaft lobes. You can still use a flat tappet cam in these situations by using oil with ZDDP protection. The zinc level in these oils provides protection for the cam lobes. There are lots of articles written on this subject and many different opinions. I know because I read a lot about it after my cam melted and it cost me about $1500 to clean out and rebuild my motor . I don't want to go through that again so I don't cheap out on the oil and I followed recommended break-in procedures. Lots of guys are switching over to roller cams to avoid this problem but it is expensive to adapt one to your flat tappet cam engine. Read up and decide for yourself.
Use Valvoline VR-1 racing oil. Easy to find at NAPA, and it has 1200-ppm of ZDDP, double the amount of other oils to keep the cam and lifters happy. Break-in is CRITICAL - 2,000-2500 RPM for at least 20 minutes. If available, add a can of GM EOS from the Chevy dealer, then change the oil. Use USA-made lifters, NO cheap-*** imports!
You should run lighter pressure springs, use a moly lube on the lifters (not the same as ***embly lube used on other parts), and a break in oil with lots of zinc (not an additive to regular oil). Some stock old used springs as long as they have sufficient travel not to bind with the higher lift cam and rocker arms. If going from say a 1.6 to a 1.7 rocker, use the old 1.6 and stock lighter tension springs for initial breakin. Spring pressure is a critical element during break in. A roller will provide much more power with a similar spec cam because the rolling motion allows the ramp on the cam to open the valve quicker. You don't have to keep it open longer, it just opens faster and allows more air in quicker. Break in is easier. Rollers cost more initially, but there is no comparison in performance.
Rollers also do not require a cam lube. Well, at least for the lifts/duration and spring pressures I am used to. Possible they might with big cams and high spring pressures, best bet if you go with a roller is to ask the manufacture of the cam, not the place you bought it from, what they recommend.
We did a lot of work to extend cam and tappet-life during my career in engine development for a Diesel engine manufacturer. Lots of oil formulation and qualification development too. The whole industry ended up going to roller followers, and it wasn’t because there wasn’t enough zddp in the oils. Bottom line is that a roller follower design allows for a more aggressive valve lift curve, for improved engine volumetric efficiency, at lower cam and tappet hertz stresses, which translates to longer life. Old cars, even the high performance versions, had relatively mild cam events and valve lift curves, with moderate spring pressures. So called modern cams pushed by the aftermarket ignore the old design rules of thumb and push the design limits, which results in higher failure rates than we remember from our youth. That’s not to say there haven’t been design or quality issues with relatively mild production cams in the old days. Molar big blocks, Ford 2300 , Chevy small blocks, and Pontiacs all had cam failures in the 70s, that I have personally experienced. It’s just that the so called modern cam designs push the limit, and have higher fail rates.
as far as small block Fords, you can use the stock Ford roller hydraulic lifts. they are less than $150.00 for the set. the block can easily be modified for the spider that keeps the rollers in line. But I agree, if it is a mild cam, flat tappets are fine with the proper breakin and lubrication, I use the valvoline VR-1.
So if you have had a car built before 1985 and it had pushrods it was at least a 99% chance it was a flat tappet.
I’ve built many hi performance engines with flat tapper cams. Always broken in properly with cam lube & high zinc oil & never had a problem. Sent from my iPhone using H.A.M.B.
YOU SURE?????....Older (non-roller) blocks don't have tall enough lifter galleys to accommodate the taller roller lifters...do they?? Older SB Fords can be retro fitted for roller cams but not FoMoCo roller lifters.........can they?! 6sally6
we were required by the rules to run flat tappet cams in our dirt track cars. I broke the cam in with straight 30 weight Rotella for the older diesels with flat tappet cams. After break in I would switch to Schaffers semi synthetic 15-40 . we ran every Friday night for 26 weekends without a cam failure. I built engines for other racers with both solid lifters and hydraulic lifters depending on the cl***. I probably had 6 or 8 engines out there at any given time . I worried more about jerking a connecting rod in half because most of the cl***es had to run stock GM rods. with press fit wrist pins and just ARP rod bolts turning 7 grand lap after lap.
I beleive the top of lifter bore to deck is .500 or so less [closer] in a roller block. The OEM roller lifter is longer so the dog bone flats will be about that .500 above the non-roller block lifter bores. Got a sketch of the dimensions in my note book.
I agree with you on almost everything. The ISB ***mins is currently the most popular engine on the medium duty side, and it does not have a roller cam. However, it does have very large diameter mushroom tappets. Maybe that’s the difference. I’ve been a Diesel mechanic for 29 years and have not seen an ISB cam failure yet (knock on wood, my daily is an ISB). I have replaced quite a few roller cams in diesels that have failed. Most of the time it’s because the bearings in the tappet fail. The lone exception would be the International DT series that breaks the tappet retainer allowing the tappet to rotate and then being turned into a machine tool for the cam lobe. Sent from my iPhone using The H.A.M.B. mobile app
Right on Andy. I was a CAT truck engine tech for 20 years, replaced a lot of roller cams mostly due to roller lifter failure.
Problem is if you're not running a "popular" V8. You know SBC, SBF, SBMOPAR -the belly ****on engines as some call them. Doc Forman built an interesting tall deck Dodge hemi with custom adapted hydraulic roller lifters. This included a price tag that many of us couldn't hope to replicate. What if your in love with the Y-Block Ford, good luck putting roller lifters in place of the factory mushroom lifters. There are many others out the too. What I'm saying is you got to dance with the girl you brought to the dance. Not every girl knows the latest steps. -Dave
Another option is the Camsaver lifters being offered by a couple manufacturers. These are hydraulic lifters with an oil groove cut on the outside to direct oil right to the cam lobe for extra lubrication. As far as performance of roller verse hydraulic, if all is equal, you will not see any difference. Roller cams have the ability to open the valves faster without cam wear, but you also gain a bunch of valve train weight which requires a bunch more valve spring pressure to control the added weight. If both cams have identical spec's, they will run identical !
I forgot to post that on my last mopar cam I had it nitrated by Comp, it's a .600 lift 282 duration @ .050 flat tappet that requires stiff springs. All I can say so far is that it survived breaking in and the dyno pulls.
If two cams have identical specs but one is a roller the roller lifters can accommodate a more rapid rate of lift, in effect that creates more area under the curve. Another way of saying “....more area under the curve” is there is more time for cylinder filling even though the duration is the same.
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